@media screen and(min-width:1100px) {
  .main {
    flex: 1;
    display: flex;
    justify-content: center;

    background-color: #ccc;
    .main_box {
      flex: 1;
      display: flex;
      margin-top: 30px;
      max-width: 1320px;
      justify-content: space-between;
      .left {
        flex: 3;
        height: 500px;
        border-radius: 16px;
        background-color: saddlebrown;
        margin-right: 15px;
      }
      .register {
        flex: 1;
        height: 500px;
        border-radius: 16px;
        background-color: skyblue;
      }
    }
  }
}

@media screen and(min-width:1000px) and(max-width:1099px) {
  .main {
    flex: 1;
    display: flex;
    justify-content: center;

    background-color: #ccc;
    .main_box {
      flex: 1;
      display: flex;
      margin-top: 30px;
      max-width: 1320px;
      justify-content: space-between;
      .left {
        flex: 1;
        height: 500px;
        border-radius: 16px;
        background-color: saddlebrown;
        margin-right: 15px;
      }
      .register {
        display: none;
        flex: 1;
        height: 500px;
        border-radius: 16px;
        background-color: skyblue;
      }
    }
  }
}
